Male Gadwalls are characterized by their intricately patterned gray, brown, and black plumage, a black rump, and a white wing patch (speculum) that is visible in flight. Female Gadwalls are more subtly colored, resembling female Mallards, but with a thinner, darker bill and a white speculum. Both sexes have a white belly and a grayish-black bill.

Male Gadwall:
• Breeding (Alternate) Plumage: Grayish-brown overall, with finely patterned wavy lines on the back and flanks.
• Head: Light brown or grayish-brown.
• Wings: A chestnut (cinnamon) patch on the forewing, and a prominent white speculum (a patch of feathers on the wing).
• Rump: Black.
• Bill: Black.
• Belly: White.
• Other: Can appear to have a steep forehead.
• Non-breeding (Eclipse) Plumage: More similar to the female, but still with the distinctive male wing pattern and typically greyer above and with less orange on the bill.

Female Gadwall:
• Overall: Mottled, sandy-brown with a buffy tan appearance.
• Bill: Orange with variable black markings.
• Belly: White.
• Wings: A small white speculum.
• Head Shape: May appear square-headed with a steep forehead.
• Distinguishing Features from Female Mallard: Thinner, darker bill, and a white speculum.